Trisomy 13: What is it? Causes, Symptoms, Diagnosis, Types, Risk of Recurrence and Treatment

Patau syndrome is a severe and rare genetic disorder caused by having an extra copy of chromosome 13 in some or all of the cells in the body.

She is also called trisomy 13.

Chromosomal abnormalities are one of the most common causes of miscarriage and stillbirth.


In a condition known as trisomy, an affected individual has three copies of a particular chromosome instead of two (humans are assumed to have 46 chromosomes, 23 pairs).

There are several different types of trisomies:

Patau syndrome is the most serious of the trisomies.


Babies with Patau syndrome will likely have characteristic physical abnormalities, intellectual disabilities, and problems with their internal organs.


Most affected babies die in the first month after birth or within the first year due to health complications associated with the disease.

About 1 in 16,000 babies is born with Patau syndrome. Researchers believe that about 95 percent of babies with Patau syndrome are aborted or stillborn. No one knows why some survive to term while others do not.

Many babies that survive do not live beyond their first week. Only 5 to 10 percent make it to their first birthday.

Diagnosis of trisomy 13

Prenatal screening tests such as the alpha-fetoprotein test and pregnancy ultrasound can reveal markers of possible chromosomal conditions but cannot provide a diagnosis.

Only genetic tests such as amniocentesis and chorionic villus sampling (CVS) can provide a definitive diagnosis.

It is also possible that Patau syndrome could be revealed as the cause of pregnancy loss if the couple searches for genetic karyotype after miscarriage or stillbirth.

Types of Patau syndrome

As with other trisomy disorders, there are three types of Patau syndrome:

  • Complete trisomy 13 – is the most common type. People with this type have three complete copies of chromosome 13.
  • Partial trisomy 13: People have two complete copies of chromosome 13 and an extra part of chromosome 13.
  • Mosaic trisomy 13: Some of the cells in the body had three copies of chromosome 13, while others had two regular copies.

Risk of recurrence

Most of the time, the cause of trisomy 13 is a random error in cell division during the formation of the egg or sperm, which means that the problem is present at the time of fertilization.

In this case, the disorder is unlikely to recur. In rare cases, the father may have a balanced translocation involving chromosome 13.

People with a balanced translocation are at higher risk of having a child with partial trisomy 13 again.

Treatment and decision

One of the first questions that may be asked if your baby is diagnosed with Patau syndrome is whether you want to continue the pregnancy (or undergo intensive intervention if the baby is born with health problems).

During pregnancy, some parents choose to terminate babies diagnosed with Patau syndrome due to the generally poor prognosis and a desire not to prolong the pain of the loss.

Others continue the pregnancy because of anti-abortion beliefs or because they would rather spend some time with the baby, even if it is short.

The same applies to babies diagnosed after birth. Some parents choose only comfort care, while others opt for intensive medical interventions, although the chances of the baby surviving infancy are slim.

If your baby has been diagnosed with Patau syndrome, he may experience many emotions, from pain to anger to numbness to simply feeling overwhelmed.

It is okay to take your time and process the situation before moving on and making decisions or plans. There is no “right” way to feel and no “right” course of action to take with these diagnoses. You have to do what you think you can live better; the answer is different for everyone.

Regardless of your decision, it is okay to mourn the loss of the baby you hope to have. It may be helpful to join support groups for parents of babies with Patau syndrome or other chromosomal severe disorders.